I've finally got into the habit of making my steps every day. Diet changes are working for me, and I found a way to make myself drink enough water..... Then I wake up sick and it all seems shot.

I know myself. If I have to spend 3 or 4 days on a couch trying not to cough up a lung, it's going to break me of my healthy habits. Once I start feeling better, I'll still want to sit on the couch and watch my shows or read a book - not take a walk around the neighborhood. If I give into my cravings for comfort foods, it'll throw off my diet.

How do I stay on the right track even if I have the flu?

It is all mental at this point @KysTheIntrovert. You are still thinking of yourself as a non-active person. But that is no longer accurate. You are now and have been for some time an active person. Right? Getting sick happens in life and we all have to work around it. You’ll have to take it easy for a few days, but that doesn’t mean you can’t stand up to watch part of your shows, instead of sitting on the couch the whole time. If you are awake get up and move around 10 minutes every hour. Nothing aerobic, just a little movement. And look to get a walk in around the block as soon as you feel up to it. Get rest, but don’t baby yourself.

Also stay focused on your diet changes. No ‘comfort’ or feeling sorry for yourself food. And continue to drink water. You especially need to do that when you are feeling sick and don’t want to drink/eat anything. It is very easy to become dehydrated while on the flu and fool yourself into thinking there is actually some ‘plus’ to being sick because you actually ‘lost’ a few pounds. That kind of loss is not real and will be back quickly once the flu passes.